I wonder if anyone else experienced this issue, because i found nothing in google about it.
My gh4 sometimes makes corrupted files, this happens usually closer to the end of shooting day. More often when shooting 96 fps.
I tried HD Video Rerair Utility 1.9 - it didn't help.
I opened these files in hex editor, it seems like they miss the headers (they contained only random video data while normal gh4 videos have headers in the beginning, before this data). Some of them had a lot of error messages ("[ERROR] NeAACDecInit2 error..")
Tried to copy header from working file to the corrupted - it did't work either.
My SD cards are Kingston SDA10/256GB SDXC and Kingston SDA10/64GB SDXC, and this sh*t happens with both.